Reinforcement chair



United States Patent O 3,360,897 REINFORCENENT CHABR Melvin H. Beckman, Rockford, Ill.,'assignor to National Lock Co., Rockford, Ill., a corporation of Delaware Filed Oct. 22, 1965, Ser. No. 500,518 8 Claims. (Cl. 52-684) The present invention relates to a reinforcement chair u-tilized in a concrete form for the manufacture of precast post or pre-tensioned concrete construction or pouredin-place concrete construction and more particularly to a novel reinforcement chair formed of a plastic or like material which is utilized to maintain the spacing, imbedrnent and other relationship-s of reinforcing elements to be imbedded in the concrete construction.

The present method of obtaining the desired design configurations, structural requirements and fire protection involves the use of a metal reinforcement chair, usually of spring steel, which requires stamping, forming, heat treating, annealing and plating. Quite often the plating is chipped or scratched in the process of manufacturing, shipping or handling at the job site and corrosion occurs, and the resultant oxidation bleeds to the concrete surface causing discoloration and an unsightly condition which in many cases is visually objectionable and not acceptable. The present invention obviates these objections by providing a reinforcement chair formed of a material having the characteristics of a plastic composition that will not support oxidation for supporting reinforcing elements in the concrete form.

An important object of the present invention is the provision of a reinforcement chair having a configuration that develops a stronger structural quality, weighs less and is less costly to ship than prior types of metal chairs. The present reinforcement chair is formed of a plastic or like material which will not support combustion or transmit heat to the imbedded reinforcement element and will never corrode and thereby eliminate the oxidation problem presently encountered.

Another object of the present invention is the provision of a novel reinforcement chair which will accommodate many sizes of reinforcement rods, wire strands or bars. The chair includes outer legs or wings and is so contoured that these legs project slightly more from the point of reinforcement toward the concrete form than the center portion or column of the chair. The upper ends of the legs are shaped to provide clamping jaws which will retain the reinforcement element with the latter element snapping into position in the chair.

A further object of the present invention is the provision of a reinforcement chair which is placed in a concrete form and the reinforcement rod, wire strands or bar is snapped into place between the clamping or retaining jaws. When forces are applied to the chair by the weight of the reinforcement elements, by workmen and equipment or by the placement of the concrete and the vibration thereof, the chair is designed so that these forces will cause the legs or wings thereof to spread slightly and thereby increase the clamping pressure of the jaws on the reinforcement elements and hold the reinforcement elements more firmly in the desired anchored position.

The present invention also comprehends the provision of a reinforcement chair having a center leg or column with approaches and contacts the formwork as the legs are spread by forces applied to the c'hair. The center leg contacts the formwork in such fashion as to develop an axial load, not eccentric, on the center leg and thereby utilizes the center leg in the most eflicient structural manner.

Further objects are to provide a construction of maximum simplicity, efliciency, economy and ease of assembly, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.

In the drawing:

FIGURE 1 is a partial top plan view of a concrete form having reinforcement elements arranged therein prior to the pouring of concrete with the reinforcement chairs of the present invention supporting the reinforcernent elements at spaced locations thereon.

FIG. 2 is an enlarged vertical cross sectional view of the chair and reinforcement element taken on the line 2-2 of FIG. 1.

FIG. 3 is a view similar to FIG. 2 but with a load or force applied downward on the chair.

hFIG. 4 is an end elevational view of the reinforcement c a1r.

FIG. 5 is a side elevational view of the chair.

FIG. 6 is a top plan view of the chair.

Referring more particularly to the disclosure in the drawing showing an illustrative embodiment of the present invention, FIG. 1 discloses a concrete form 10 for making a precast post or pre-tensioned concrete construction and/or a form for poured-in-place concrete construction; the form 10 including a base or floor 11 and one or more side walls 12. A plurality of reinforcement elements 13such as rods, wire strands or bars, are positioned within the form in spaced position and are supported in theform spaced from the-base of oor 11 by a plurality of reinforcement chairs 14. The chairs are positioned at spaced intervals along the reinforcement elements.

The reinforcement chair 14 is formed of a rigid structural plastic or like material that will not corrode or support oxidation. The material of the c'hair will also remain sufciently rigid to perform properly when high temperatures are imposed upon it and also will not become brittle when utilized in low temperature. The material used will not support combustion. One such suitable plastic material is rigid polyvinyl chloride.

The reinforcement chair 14 includes a concave reinforcement element center rest 15 having a center post or column 16 depending therefrom. On either side of said column and diverging downwardly and slightly curving downwardly and outwardly are a pair of leg members 17, 17, terminating in feet 18, 18. Extending upwardly from the feet are a pair of outwardly bowed converging clamping jaws 19, 19 which terminate at their upper ends in outwardly extending and inclined carmning flanges or projections 21, 21. The clamping jaws converge, but are spaced apart suiciently above the center rest 15 to spread apart and permit entry of a reinforcing element 13.

The reinforcement chair is shown in its normal position in FIG. 4 prior to insertion of an element 13. The element 13 shown in FIGS. 2, 3 and 4 has a diameter greater than the spacing of the clamping jaws 19, 19, and when the element is moved downward, as indicated in FIG. 4, it engages the flanges 21, 21 to cam or spread the jaws 19, 19 apart and snap into position upon the rest 15 as shown in FIG. 2. Also as shown in FIG. 2, the center leg or post 16 is spaced up-wardly from and out of contact with the base or floor 11 of the form 10 so that only the feet 18, 18 contact the form.

When forces are applied to the chair 14, as shown by the arrows in FIG. 3, such as the weight of the reinforcement element 13, by workmen and equip-ment being placed on the reinforcement elements or by the placement of the concrete and the vibration thereof, these forces cause the leg members 17, 17 to spread slightly and increase the pressure of the jaws 19, 19 on the reinforcement element 13 and thereby more firmly retain the reinforcement element anchored in the desired posi- 3 tion. As the legs 17, 17 are spread slightly, the center post 16 is depressedy and contacts the base 11 of the form 10 so as to develop an axial load on the center post 16 and thereby use the center post in the most efficient structural manner.

tensioned concrete construction, in poured-in-place re-l inforced concrete Yconstruction or in other reinforced concrete configurations.

Having thus disclosed my invention, I claim: 1. A reinforcement chair for the positioning of a .reinforcement element in a concrete form, comprising a concave center rest having a center post depending therefrom, a pair of diverging legs depending from the center rest and terminating in feet, and a pair of converging clamping jaws extending upwardly from said feet beyond -said center rest and spaced apart a distance less than the diameter of the reinforcement element.

' 2; A reinforcement chair as set forth in claim 1, in which the depending end of the center post is normally spaced above the iioor of the concrete form when vthe feet rest upon the oor.

3.'A reinforcement c'hair as set forth in claim- 1, in which said clamping jaws extend upward from said feet and terminate in outwardly diverging cam-ming anges which are engaged by the reinforcement element to spread the jaws apart so that said element snaps into position betewen the jaws and rests on the center post.

4. A reinforcement chair `as set forth in claini 1, in which said legs are slightly inwardly bowed and said clamping jaws areA slightly outwardly bowed.

5. A reinforcement chair as set forth in claim 1, in which forces applied downward on said chair cause said legs to spread slightly resulting in increased pressure exerted by said clamping jaws upon said reinforcement element. r

'6. A reinforcement chair as set forth in claim 5', Vin which vsaid forces cause the center post to approach and engage the `form so as to develop an axial load thereon.

7. A reinforcement chair as set forth in claim 1, in which the chair is formed of rigid plastic material.

S. A reinforcement chair as set forth in claim 1, in w'hich said chair is formed of rigid polyvinyl chloride.

References Cited UNITED STATES PATENTS 1,441,357 1/1923 Lampert 52,--6'84 1,499,983 7/1924 Heidrich 52-689 '1,841,743 l/ 1932 Lampert SLL- 688 3,280,529 10/1'966 Reuss 52-689 FOREIGN PATENTS 986,450 3/1965 Great Britain.

FRANCIS K. ZUGEL, Primary Examiner. 

1. A REINFORCEMENT CHAIR FOR THE POSITIONING OF A REINFORCEMENT ELEMENT IN A CONCRETE FORM, COMPRISING A CONCAVE CENTER REST HAVING A CENTER POST DEPENDING THEREFROM, A PAIR OF DIVERGING LEGS DEPENDING FROM THE CENTER REST AND TERMINATING IN FEET, AND A PAIR OF CONVERGING CLAMPING JAWS EXTENDING UPWARDLY FROM SAID FEET BEYOND SAID CENTER REST AND SPACED APART A DISTANCE LESS THAN THE DIAMETER OF THE REINFORCEMENT ELEMENT. 